Accompanying recent popularization of computers, an inkjet printer is widely used for printing letters or an image on paper, film, cloth or the like not only in offices but also at homes.
The inkjet recording method includes a system of jetting out (ejecting) a liquid droplet by applying a pressure using a piezo element, a system of jetting out a liquid droplet by generating a bubble in an ink under heat, a system of using an ultrasonic wave, and a system of jetting out a liquid droplet by suction using an electrostatic force. The ink composition used for such inkjet recording includes an aqueous ink, an oily ink and a solid (fusion-type) ink. Among these inks, an aqueous ink is predominating in view of production, handle ability, odor, safety and the like.
The coloring agent used in such an ink for inkjet recording is required to have high solubility in a solvent, enable high-density recording, provide good color, exhibit excellent fastness to light, heat, air, water and chemicals, ensure good fixing on an image-receiving material and less blurring, give an ink having excellent storability, have high purity and no toxicity, and be available at a low cost. However, it is very difficult to find out a coloring agent satisfying these requirements in a high level.
Various dyes and pigments for inkjet use have been already proposed and actually used, however, a coloring agent satisfying all requirements is not yet found out at present. Conventionally well-known dyes and pigments having a color index (C.I.) number can hardly satisfy both color hue and fastness required of the ink for inkjet recording. Studies have been heretofore made on dyes having good color and fastness with an attempt to develop an excellent coloring agent for inkjet use. However, in the compound called a water-soluble dye, a water-soluble group is necessarily substituted. If the number of the water-soluble groups is increased to as to enhance the stability of ink, this has been found to incur a problem that the image formed is readily blurred under high humidity conditions, that is, it is difficult to combine the stability of ink and the resistance against blurring.
In silver salt diffusion transfer, it is described in JP-A-3-63648 that carbonyl aceto compound can be used to prevent blurring of a transferred image. Also, in JP-A-2-309352, it is described that carboxy ester or sulfo ester can be used for the same purpose. However, it had not been considered about such method for preventing of blurring in the field of a transferred image of ink jet recording using other kinds of dyes.